Why Can't We: Drive Cars Equipped with Solar Panels

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Solar cars do exist—mostly in the form of impractical racing machines developed by university organizations to compete in renewable-energy challenges.

The problem with these bizarre-looking rides is that they’re practical only in ideal circumstances. Says George Hansel, aerodynamic-design leader of MIT’s Solar Electric Vehicle Team: “If we took our solar car and used it as a commuting vehicle in Albuquerque, New Mexico, where speed limits are 40, it’s usually sunny, and you’re rarely driving more than 200 miles a day, you’d have a very light one­-person commuter vehicle that would essentially run all the time.” This, he calculates, would require about 65 square feet of solar panels.

But it wouldn’t work well outside the city, where ­faster speeds mean increased reliance on battery packs. At that point, you may as well take the solar panels off the car, put even larger ones on a building—where they can be pointed in a more effective direction and are less susceptible to ­damage—and use that energy to charge an electric car that could run rain or shine.

The alternative would be producing a car with a solar array the size of a trailer-truck roof: for every gallon of gasoline a car consumes to travel 100 miles on the highway, the equivalent solar version would require 375 square feet of panels. Good luck parking that puppy.